The androgen receptor (AR) is a nuclear receptor that is the primary therapeutic target of prostate cancer (CaP). This grant concerns characterization of a cellular pathway that regulates AR activity, which could produce new therapeutic targets, and the application of a novel screening strategy to identify small molecules that inhibit AR function. We hypothesize that the Rho/ROCK/LIM kinase (RRL) pathway regulates AR activity through alterations in the actin cytoskeleton. I will use prostate carcinoma lines that stably express native and fluorescently-labeled AR to determine how the RRL pathway influences the folding, dimerization, nuclear import, and transcriptional activity of AR. We also hypothesize that compounds that inhibit AR ligand-induced conformational change may reveal novel anti-androgens that would be missed by traditional screens for AR inhibitors. I will use a high-throughput FRET assay to screen three collections of biologically active small molecules for compounds that inhibit AR ligand-induced conformational change. The most effective inhibitors will be examined in detailed secondary analyses to determine their effect on AR nuclear transport, dimerization, native AR-responsive transcription, and proliferation of prostate cancer cells. [unreadable] [unreadable] [unreadable] [unreadable]